NAYPYITAW, Myanmar — Myanmar's ruling junta said Friday it will let foreign aid workers and commercial ships help survivors in the cyclone-ravaged Irrawaddy Delta, but refused to relent on accepting aid from U.S., French and British military ships.

The ships, almost within sight of the coast for more than a week, offer a huge potential boost to the aid effort because they can send helicopters to the hardest-to-reach spots.

The military regime told U.N. Secretary-General Ban Ki-moon Friday that all aid workers would be let into the country as long as it was clear what they were doing and how long they would remain.

The Irrawaddy Delta, Myanmar's key rice-producing region, was decimated by Cyclone Nargis, but the xenophobic junta has kept it virtually off-limits to foreign aid workers.

An estimated 2.5 million people remain in severe need, threatened by disease, hunger and exposure because of the loss of their homes. The U.N. says only about 25 percent of survivors have received any kind of aid.

Official estimates put the death toll at about 78,000, with another 56,000 missing. Myanmar has estimated the economic damage at about $11 billion from the May 2-3 storm.

Under intense international pressure — and with an aid donors meeting scheduled for Sunday — Senior Gen. Than Shwe said he would allow in aid workers "regardless of nationality," Ban said.

Civilian ships, small boatsThan Shwe refused to relent on the landing of the military ships, however.

According to Ban, the Myanmar leader "agreed that international aid could be delivered to Myanmar via civilian ships and small boats."

The U.S., Britain and France all have warships off Myanmar's coast ready to help. But Myanmar's junta is nervous about any landings because it fears invasion or political interference. It moved its capital from Yangon, the largest city, to this town in the north in 2005 in part because of such fears.

The junta is also wary of the political and psychological consequences of its people witnessing an efficient military-run aid operation by Western nations, which they have long accused of trying to undermine the country and turn it into a neo-colony.

Patience with the junta has been wearing thin.

At the United Nations in New York, France said Thursday it would push for a U.N. resolution authorizing the delivery of aid to survivors "by all means necessary" if pressure from Ban and Myanmar's neighbors does not open the aid pipeline quickly.

Pentagon spokesman Bryan Whitman said Friday that 50 U.S. C-130 transport plane flights have been permitted into Yangon, carrying more than 480 tons of relief supplies. But they have not been allowed to fly directly to the delta.

Whitman said the ships — led by the USS Essex — will remain for days or weeks, but will not linger for months waiting for permission to bring in aid.

"If the position of the Burmese government doesn't change, we will have to make a decision to reallocate those Navy assets," he said.

Ban, who returned to Bangkok Friday, said details on moving aid workers still need to be worked out, and "implementation will be key." But he stressed he believed he had achieved a breakthrough.

Aid agencies have said they are preparing barges, rubber boats and other vessels to deliver aid once approval is given.

"While the pace of aid deliveries has increased in the past week, the entire relief effort is only scratching the surface of what is needed in a disaster of this scale," said Melissa Winkler, of the International Rescue Committee. "Limited access to cyclone survivors has been the largest obstacle."

'Narrow window of opportunity'Nearly three weeks after the storm, the U.N. Food and Agriculture Organization warned Friday that hundreds of thousands of people have insufficient food, and prices for rice, cooking oil and other basics have doubled throughout the country.

Only a "very narrow window of opportunity" remains to provide seeds and other material to farmers before the rice-planting season begins in a few weeks, the agency said.

The International Red Cross said rivers and ponds in Bogalay remained full of corpses and many people in remote areas had received no aid.

"This is a significant step forward, and could be a turning point in the aid response," Brian Agland, who heads the U.S.-based aid group CARE in Myanmar, said of Ban's trip.

Even getting into Myanmar was progress for Ban, who will return for the Sunday donors meeting.

The 76-year-old Than Shwe — reclusive, superstitious and known as "the bulldog" for his stubbornness — had refused to answer Ban's calls from New York or to respond to two letters.

Politics avoidedBut the junta allowed Ban to fly to the remote capital of Naypyitaw early Friday after taking him on a carefully choreographed, four-hour helicopter tour of the disaster zone Thursday.

Ban tried to avoid political hot-button issues.

U.N. officials in Myanmar said the fate of opposition leader Aung San Suu Kyi — whose latest period of detention expires Monday — was not discussed at the meeting. A string of U.N. envoys have in the past failed to spring the Nobel Peace Prize laureate from house arrest.

Ban also did not comment on a constitutional referendum to be held in Yangon and delta areas Saturday that critics say is a pretext to strengthen the military's political footing.

Though his work for Myanmar is still far from completed, Ban will fly to Chengdu in China on Saturday to inspect the damage done by the May 12 earthquake there, members of his entourage and the Chinese foreign ministry said.

On Sunday, Ban will attend a donors conference in Yangon and the U.N. said Friday that more than 45 countries and regional organizations plan on participating. The session is aimed at raising funds for immediate humanitarian assistance. The United Nations has already launched an emergency appeal for $201 million, and has so far received about $50 million in contributions and about $42.5 million in pledges, officials said.

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